Bell's Theory with no Locality assumption

By root - Posted on 09 junho 2011

Palestrante:

Charles Tresser, T.J. Watson Research Center, IBM

Data:

Terça-feira, 26 Abril, 2011 - 16:00

I will prove versions of Bell's Theorem and (if time permits) of the GHZ Theorem (the Bell Theorem without inequalities) that do not assume Locality but only assumes the Effect After Cause Principle according to which for any Lorentz observer the value of an observable cannot change because of an event that happens after the observable is measured. I show that the Effect After Cause Principle is strictly weaker than Locality. As a consequence of our main Theorems, Locality cannot any more be considered as the common cause of the contradictions that one succeeds obtaining in all versions of Bell's Theory. All versions of Bell's Theorem, including ours, assume Weak Realism (Stapp's Contrafactual Definiteness), according to which, in particular, an observable has a value that is well defined whenever the measurement could be made and some measurement is made. As a consequence of my results, Weak Realism gets promoted as the only common hypothesis to the contradictions that one succeeds obtaining in all versions of Bell's Theory. Usually, one avoids the contradiction that one reaches in Bell's Theory by assuming Non-Locality; this would not help in our case since we do not assume Locality to begin with. This work indicates that it is indeed (Weak) Realism, and not Locality, that needs to be negated to avoid contradictions in microscopic physics. If time, and timing of our work permit, I will also cover work in progress with Edson de Faria.